The key to building and maintaining users' confidence in long running applications is fault tolerance. Not just a data and connectivity concern - fault tolerance should be considered at every level of your application. A fault tolerant application clearly conveys its state to users throughout its interface, allows users to remain as productive as possible in any particular state, and ideally works behind the scenes to recover from faults. This talk will cover UX patterns and engineering strategies for building fault tolerant Ember.js applications.